T4i Lens Advice

Hi Everyone, first time poster. I recently sold my 400D and am thinking about upgrading to a t4i. I am going on Safari in Africa in the fall and want to carry the right lenses. I had recently bought a 70-300 IS USM (4.5-5.6) lens for my 400D. I sold the sigma lenses I first bought with it and kept the USM lens. I hope to use the t4i as a complete package to do video and still photography of Africa and beyond. My request for advice is what lens I should choose with the t4i to have the spectrum covered as much as possible. The options I am considering:

the 2.8 STM pancake lens- this would cover my short range needs and with 2.8 could handle most low light situations. The STM would work for video at close ranges with conversation or background noise that I wouldn't want drowned out with focus noise. I am also not thrilled with how the screen locks if removed while zoomed I saw on digitalRevcom on youtube. I also couldn't interchange filters with my USM lens

the 18-135 STM lens - this would cover a lot of situations and I feel I wouldn't be switching lenses and risking dust intrusion as much as the shorter lens. I do fear that its not fast enough for when I want to take night photography or low light action. It also seems to be big and in combination with my USM lens a lot of weight in a limited packing situation.

a kit 18-55 IS (3.5-5.6) - quick and dirty, standard no frills lens, decent for the short game where my USM lens can take the long game and the occasional macro. I've seen this attached to the t4i kits in best buy and Ritz and its noisy.

a 50mm fast lens-if I were to go with my 300mm USM and the 135 STM lens I almost feel I would have to get a smaller fast lens for low-light shots. The cost of my lens package is a concern and so is weight and bulk but I don't want to regret not having a lens to cover most situations.

I'm not really sure what package/kit I should go for. As I mentioned, its my second safari so I expect a mix of scenery shots, animal close ups, portrait people and scene shots and I want to be able to take quality video without constant adjustments and too much noise (I will probably overlay music, but I still don't want anything too noisy.

Can you experts perhaps steer me towards the right path or perhaps just give some pros and cons of the options above? Thank you.